Honda Foundation (a public-interest incorporated foundation created by Honda Motor Co Ltd’s founder Soichiro Honda and his younger brother Benjiro Honda) says that the Honda Prize 2017 will be awarded to Kyoto University professor emeritus Dr Hiroyuki Matsunami for his contributions to pioneering research on silicon carbide (SiC) power devices and their practical applications.
The award ceremony will be held at the Imperial Hotel in Tokyo, Japan on 16 November. In addition to the prize medal and diploma, the laureate will be awarded 10m yen.
Matsunami is the 38th Honda Prize laureate. Established in 1980, the Honda Prize is Japan’s first international award in the field of science & technology. It is awarded annually to an individual or group in order to recognize accomplishments in the field of ecotechnology (advancing human achievement while concurrently preserving the natural environment). Through Matsunami’s research, SiC power devices have been put into practical use and are contributing to reducing power loss in the control of power supplies.
Research on SiC began in the USA in the mid-1950s. Matsunami had an interest in SiC from early on, and started basic research in the late 1960s to develop electronic devices utilizing SiC’s excellent physical properties of high-temperature operability and radiation resistance.
While silicon has the characteristics of a single crystal with a regular diamond structure, SiC is a hard-to-handle material, as achieving crystal growth with few defects is difficult. Also, SiC has 200 different types of crystal structure (polymorphism), so the most appropriate crystal polymorphism for commercialization was difficult to determine. Furthermore, with a robust structure as hard as diamond, processing SiC is extremely difficult and challenging. Although many research institutes attempted to realize the practical application of SiC, none overcame the processing difficulties and most of them withdrew from the project.
Matsunami continued basic research on SiC and, about 20 years after starting his research, in 1987 he published a method ‘Step-Controlled Epitaxy’, enabling the production of a homogeneous SiC thin membrane with uniform crystal polymorphism by tilting the surface of the substrate a few degrees. Around 1990, as silicon power devices were approaching their performance limit, due to his discovery the use of SiC came under the spot light and the development of SiC power devices progressed dramatically.
Around 2010, the practical application of SiC power devices began. Using SiC in power devices led to a tremendous reduction in power loss, enabling high-speed, high-efficiency power control. Likewise, as SiC has high-voltage resistance and high-temperature resistance characteristics, cooling systems became more compact, leading to the downsizing of power control mechanisms. In 2013, SiC power devices were introduced to the Tokyo Metro subway, yielding a 30% energy reduction compared to the energy required by conventional train cars. In recent years, SiC power devices have been installed on suburban trains, high-speed elevators, power conditioners for solar batteries, and fuel-cell vehicles. Also, experiments for installation on hybrid cars and the Tokaido Shinkansen bullet train have begun.
Although there are still some challenges to the wider adoption of SiC power devices (including the establishment of mass-production technology, cost reduction, etc), its application to electric vehicles is also anticipated, after a further reduction in power consumption, space-saving through downsizing of the devices, and cost reduction are achieved.
Beginning with Step-Controlled Epitaxy, SiC production methods and the technologies enabling practical applications to power devices have paved the way for new possibilities for SiC as a novel material. As realization of the practical uses of SiC power devices can also lead to mitigating the rapid increase in fossil fuel consumption and the amount of waste from power generation accompanied by a surge in consumption globally, Matsunami’s accomplishments were hence considered appropriate for recognition with the Honda Prize.
